Friday, October 21, 2016

Testing New Dethermalizers

As I am advancing from building and flying free flight model airplanes purely for the fun of watching the models fly to flying in competition, I am trying to find out what works for me.  This includes improving my building skills and the products used in completing the models. Recent blog articles have been about the Gizmo Geezer propeller system but I have also been experimenting with dethermalizer systems trying both old and new technology. 

BSD DT Only Electronic DT

In addition to bringing the plane down from a thermal, because of the small flying sites I fly from at times the DT is used to terminate the flight before the airplane flies off the field into a tree. The first DT’s I used were viscous timers on discus launched gliders, for short flights I was able to control it fairly accurately.  When I installed a viscous timer on a P30 model that was making longer flights I found that a lot of adjusting needed to be done to get over 2 minutes before the DT released. It is not just a matter of winding the dt farther as that puts more tension on the spring resulting in the DT running faster. By a lot of trial and error with adjusting spring tension I could get 2 minute DT time but not that accurately.

Fuse DT Guillow's Lancer

From the free flight contests I have entered this year, it is apparent the use of a burning fuse is very prevalent. It is light and relatively inexpensive; with some experimenting it might be fairly accurate. To get some idea how long the fuse would burn for a given length I did some tests burning the fuse hanging out of a tube with a rubber band at the edge of the tube, like how the snuffer tube would work in an airplane. I timed the burn times and found it fairly predictable, so I modified a rubber model I have been flying the Guillow’s Lancer to use a fuse to release the front of the wing bringing the airplane quickly. Some short test flights with the Lancer and the fuse DT looked promising.

E36 in Flight

After using the Texas Timers electronic DT in my e36 model, electronic DT seemed like the ultimate solution. At the Nats and one of the local contests I talked to people using an electric band burner DT on rubber powered models. I ordered one from Starlink for the Wilbur old time rubber model I am building. BSD Micro sells some really lightweight electronic timers that I wanted to try so I ordered one for the E20 event which controls the motor and has a tiny built-in servo to DT the model. There is a rotary dial programmer box available to set the times so I ordered that as well.  In addition I ordered the DT Only unit to try on rubber powered models; this unit only weighs 1.5 grams without 

Starlink Band Burner DT

Charger for Band Burner

BSD Micro E20 DT
Programmer for E20

DT Only

Watch for additional blog posts as I install and the test the various DT methods. I also have the Texas Timers - Micro DT that I will be installing in a hi-start glider.

Bill Kuhl

Vendors Related to this Article  BSD Micro RC  - E20 and DT Only  Gizmo Geezer – rubber propeller systems  Guillow’s  - Lancer sport rubber model Wilbur rubber model Discus Glider with Built-in DT  - E36 Pearl e202  Starlink Flitetech – band burner  Texas Timers – electronic system for e36

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Thursday, October 13, 2016

Flying With the Gizmo Geezer

This past weekend I had the chance to fly my NJAPF P30 rubber power model with the Gizmo Geezer installed on a large field in a contest. It worked well with the exception that apparently I didn’t have the shielded sleeve connected properly and it came loose right after winding. The rubber retracted in a hurry back to the rear peg. Luckily damage to the fuselage was just some ripped tissue and I continued to fly the airplane.  I am worried about losing the winding attachment and need to connect it permanently to the blast tube wire.

My P30 using Gizmo Geezer Propeller

Covering Ripped When Connector Came Loose

Inside the Blast Tube
The airplane climbed out well although other P30 models were greater performance designs with rolled tube fuselages. Just the same it placed about halfway in the standings, with one flight the timer lost sight of my plane just as it made a max. I notice Clint Brooks includes the Gizmo Geezer in his Monarch and Boomer Mk III P30 model kits.  I also noticed many of the scale models at the 2016 Nats in Muncie Indiana had Gizmo Geezer propellers.

Gadfly with Gizmo Geezer

Nose Block Sold by Volare Products

I had emailed George Bredehoft of Volare Products
 with a couple questions about the Gizmo Geezer and the nose blocks he sells, I had purchased the generic one but he has special nose blocks to fit certain airplanes. The main purpose of the nose blocks is to get the perfect fit for the nose button which has three bumps sticking out of the round hole. George sells just the Gizmo Geezer nose buttons because some customers want just the ability to easily adjust thrust angles. 

Gizmo Geezer is located in Canada and the company consists of Orville Olm and Marcy Green. There is a lot of information on their website, a good place to start is at the sitemap.

Nose Might Come Out on Landing
Nose Stays on in Glide

As far as testing out the desirable features so far the nose has always remained inside the fuselage of my plane without the rubber band fastener I had over the nose before installing the Gizmo Geezer. Many times the nose will pop out when the plane hits the ground. I have not had a need yet to try adjusting the thrust line.  As far as I can tell the rubber unwinds smoothly and the propeller free wheels easily.

I have more Gizmo Geezer propellers on order.

10-24-2016 Update

Spinner Model

Received another 9.5" propeller with the spinner and also 7" propeller.

Bill Kuhl

Related Articles

Gizmo Geezer Review Part 1

Oktoberflug Free Flight Contest

Monday, October 10, 2016

Oktoberflug Free Flight Contest

At the last minute I decided to make the drive to North Branch Minnesota for the final outdoor free flight contest of the year. It was chilly as witnessed by frost in the grass when I arrived but the wind was darn near still.  This gave me a good chance to test fly my Pearl e202 electric free flight, it flew really well but it is not adjusted how it should be for this type of model.

Pearl e202 e36 in Flight
Frosty at the Start
Next I got out my NJAPF P30 rubber powered model which was an event I entered along with HLG and CLG. Setting up the stooge still takes me awhile and then I was winding with the Gizmo Geezer propeller system for the first time. I apparently didn’t get the parts connected properly and the rubber part pulled back into the fuselage at a high speed.  Luckily it didn’t break the fuselage but ripped some holes and I made more before getting the rubber pulled out. More careful after that, the model flew well with the new propeller but the wind was coming up.

Ripped some Holes When Rubber Retracted
P30 Flying

On my final P30 flight I put in a few more turns, the viscous DT was set for hopefully 2 minutes. I started running towards it right after launch but it was drifting downwind too fast for me to keep up with it. The last I saw of it the plane was still going up.  I got to the irrigation ditch which was full of tall grass, someone warned me about trying to jump over it but I got wet anyway. No sign of my plane but I walked the soybeans for a time and gave up figuring the plane was lost. Someone returned it later but before that someone on a motorcycle had picked it up and broke the wing in the wind, I was just happy to get it back.

P30 Returned

My DLG Drifting Fast

My last flights were CLG and HLG gliders, I was almost happy when I had a short flight after so much walking. My last flight of my Dynomite DLG with a flight that was on the edge of visibility the time was only 45 seconds. That is probably where I set the DT but any longer and it would have been in the soybeans.
Young Lady at Contest

Large Rubber Model

Between the Nats week long contest and two times to the North Branch contest I am really getting excited to fly free flight models and have started building for next year. It can be harder than it looks to get some types of models flying well and to be competitive at contests really takes the effort.  Super group of people at the contests that will help you anyway they can.

Bill Kuhl

Related Articles

Minnesota Free Flight Contest near North Branch MN

Comparing Free Flight and RC Sailplane Contests

Thursday, October 6, 2016

Electric Buses and New Technology

I have to admit that I do not always embrace everything about change and new technology. For sure I think the music from the 70’s and the 80’s was much better but I have always had a fascination with alternative energy.  Clever ways to approach engineering challenges have fascinated me as well.  In 2012 I had purchased a hybrid automobile the Toyota Prius and the primary reason was because the combination of technology combined to make a vehicle that was so fuel efficient was intriguing to me.

Electric Bus

My Hybrid Car

All Electric Car
Electric Powered Model Airplane Pearl E202

Although the hybrid technology has worked well I have also felt that a pure electric vehicle was the engineering goal. For models, flying and surface based (planes, multi-rotors, cars, and boats) the new lithium batteries and brushless motors have put the performance level equal or exceeding the more conventional alcohol-type fuel engines. For transportation large enough for people to ride in the problem of not enough range between recharging has been a legitimate concern.  Recently I was passed on the highway by a Nissan Leaf which is an all-electric vehicle which has good range for most trips, but not enough for long trips.

Overhead Charging of Electric Bus

While watching a business related TV show they were interviewing the CEO from Proterra a manufacturer of electric buses. The number of cities with some electric buses operating is constantly growing as is the practicality of putting the buses in place. Although the initial cost is higher than a diesel powered bus, the cost to operate these buses should be less not just because of the price of fuel but maintenance should be less also.  Many approaches have been used or have been thought of to solve the limited range issue. Besides better batteries and lighter buses, technology for fast charging the buses while operating the bus routes has been used so that the bus can drive the route continuously. The charging station can be either above or below the bus and the driver doesn’t even have to get out of the bus to do the charging process.

Many Buses use Composite Construction that includes Balsa Wood

Another approach to powering the electric bus is very large capacitors, a capacitor is an electronic component that will quickly take an electric charge and then release it.  Some toy free flight model airplanes use a capacitor to power the electric motor in place of batteries such as the Flash Fighter. The Science Olympiad competition had a trial event to build a model airplane powered by a capacitor which I had mentored a student far away to successfully build airplanes for the competition.

SO Capacitor Plane Built by Student

Finally I want to especially Thank Eric Williams: Vice President, Academy of Model Aeronautics,District II who is running for AMA president. He provided me with all of the images of electric buses.

Bill Kuhl

Electric Bus Videos  Proterra Battery Electric Bus Endurance Test King County Metro 2016   ELN - London trials first all-electric buses  Introducing HIGER Supercapacitor (UCAP) Electric Bus

Thursday, September 29, 2016

Gizmo Geezer Review - Part 1

This is the first part of my review of the Gizmo Geezer rubber power propeller system which relates to my testing on a stand and the installation in an existing P30 free flight model I have.

Testing Gizmo Geezer on a Stand

Desirable features I saw in Gizmo Geezer Advertising

  • No additional method needed to hold nose of the model on such as rubber bands or magnets.

  • Method to do easy thrust adjustments without having to use shims.

  • Smoother unwinding of rubber motor and no need to braid the motor. 

  • The propeller would free wheel easily without the need to build additional mechanism on the propeller shaft.

  • The propeller has a higher PD ratio than similar propellers.

Getting Started

The rubber motor loops are attached to the Sleeved Clevis by inserting Sleeved Clevis Pins.  Attaching the rubber inside of the Sleeved Clevis can be a little tricky but if you gather the end of the rubber together in a bunch and work the hex wrench through the small loop with the Sleeved Clevis pin inside it goes into place fairly easy. Here I have 3 loops of 1/8” rubber.

Rubber has been inserted as seen from the rear.

As seen from the front.

The Winder Attachment is connected to the front of the Sleeved Clevis by inserting through the slot and then twisting.

Your winder is attached to the loop in the back of the Winder Attachment

After the motor is wound it is inserted into the rear of the Prop Shaft Drive and twist to connect.

After the motor is wound you can park the motor such that you do not have to hold the propeller to keep it from unwinding. When you are ready to launch you can engage the propeller again.   

With the Gizmo Geezer there is no need to braid the rubber strands in fact doing so will not let the free wheel mechanism operate properly.

Front view of Prop Drive Dog engaging the propeller.

Just before going into park mode which stops the rubber from unwinding further and propeller goes into freewheel mode. Keeping a level of tension should combat the problem of random bunching of a long motor that can negatively affect the glide. According to Gizmo Geezer website the tension is held to between 55 to 60 grams.

Propeller disengaged

There are three screws that can be turned for thrust adjustments.

Installation into Existing P30 Model

This is my NJAPF P30, note the ugly rubber band across the front of the nose to hold it in when all the tension from the rubber motor has gone out. Free wheeling is accomplished by 90 degree bend in the front of the shaft and the molded ramp with notch in the propeller. 

Gizmo Geezer PW95 propeller seen above which comes adjusted to a high performance 1.25 to 1 P/D (pitch to diameter ratio). Peck 9.5” propeller seen below.

To be continued..

Bill Kuhl


Friday, September 23, 2016

I Have a Short Fuse – on Guillows Lancer

Part of why I enjoy free flight model airplanes is there is so much to experiment with.  In the models I have built with a dethermalizer – DT, I have either used a viscous DT timer or with my electric free flight an electronic timer.  Using a burning fuse although a method that has been used for years is something I have avoided. In the two free flight contests I went to this summer I noticed many people are still using the burning fuse to bring their airplanes down.

Fuse DT on Guillows Lancer

Before building a new airplane using a fuse DT I thought I would start experimenting with an existing airplane I had, my Guillow’s Lancer would be easy to convert as the wing is held on with rubber bands. My thought was to popup the front of the wing to bring the airplane down; as the popup stab is not always adequate to bring lighter airplanes down from a thermal. Many people completely eject the wing off on lighter airplanes with a string attaching the wing to the rest of the airplane. On another airplane I will try this method. 

The Fuse is Burning

To get some idea how fast the fuse would burn and how well the snuffer tube worked, I cut some pieces of fuse and stuck them in an aluminum tube to test the burn rate using a stop watch. To light the fuse I was using a barbecue lighter which isn’t the most reliable method. Several people have given me better ideas on lighting the fuse which I will look at later.

Flying Upwards

The modifications I did to my airplane were to create a wire hook on top of the wing and on the top of the fuselage in the nose area.  From the hook in the middle of the wing a rubber band pulls the wing back while another rubber band running from the middle hook to the front hook holds the wing down in the front until the fuse burns that rubber band. Thin fishing line provides a limit to how far the wing can tip up in front. A short length of aluminum tube glued on top of the nose area is the snuffer tube that holds the fuse.

The Wing has Popped

Maybe Front of Wing Up too High

Last evening turned nice after a huge amount of rain so I decided this was my opportunity to try this out. Where I could fly from was far from where I parked so I stuffed in my pockets; fuse, scissors, small winder, rubber bands, and the grill lighter.  I knew the plane would not fly real long on the winds I could put in so I tried to make the fuse really short, and you thought I was losing my temper. 

Crashing, I Mean Landing on Grass

I made several flights and a couple of times it DT’ed about two feet off the ground. On one flight it did dt maybe 20 feet high and I snapped a couple pictures of it coming down.  The propeller was probably still turning as it came down but I was a little surprised how steep the nose was pointed down as it came down. It didn’t hurt the airplane and it should bring it out of a thermal.  The Lancer doesn’t have a good glide anyway but no doubt if it would wander into strong enough lift it could fly away.

Bill Kuhl

Related Links

Guillow's Lancer Model Airplane

Trying a New Idea on Nose Plug

Fuse I Purchased from Volare 

My Building and Flying Guillows Models Website